There are various proposals for a system in which solar energy is converted to electric power by a solar panel (solar cell panel) and a device is driven by the electric power. An example thereof may be found in PTL 1.
PTL 1 discloses a motor drive apparatus and an air conditioner. An output voltage from a solar battery is boosted by a DC-DC converter. The DC-DC converter includes a conversion circuit, a switching control circuit, and an input voltage control circuit. The input voltage control circuit controls the switching control circuit by a feedback control scheme such that the voltage at an input terminal of the DC-DC converter is not smaller than a predetermined voltage value.